1. Field of the Invention
The invention broadly relates to the field of sectional utility poles, and more particularly relates to the field of inter-connections for securing the sections of such poles.
2. Description of the Related Art
Multi-sectional utility poles are used for a variety of purposes such as highway luminaire supports and utility poles, e.g., telephone, cable and electrical. Poles of a given length are often designed in multiple sections to provide for an increased ease of transporting by truck, railroad, or even cargo plane. The length may also be restricted due to other field requirements. All such multi-section poles, however, must address the issues of joining each of the sections of pole to one another and appropriately securing the joints in the field during installation.
One common method of making multi-section poles is to use tubular sections which are uniformly tapered along their entire length such that the top is narrower than the bottom. These uniformly tapered sections are then secured to each other by sliding one section over another. The tapered sections are designed so that the bottom portion of a top section slides over the top portion of a bottom section. The portions of the two sections that are in contact, ideally, form a tight fit. There are several limitations associated with this technique.
Poles of this type are typically expensive to fabricate. Additionally, when assembling a pole vertically, it is necessary to suspend the upper sections one by one from a helicopter or crane or other device, which is expensive in terms of the equipment needed and in terms of the labor involved. Such an assembly process can also take a great deal of time. Further, the uniformly tapered sections can also be expensive to produce.
Another factor which can contribute to the cost and the time involved in assembly is a lack of fungibility between the sections. Insofar as the individual sections of a complete pole are designed to be used together for that specific pole, this requires additional sorting at the jobsite and can cause delays if the sections are not delivered in the proper order for assembly.
Accordingly, there is a need for a multi-sectional utility pole and a method of fabricating it which overcome these limitations.
Briefly, in accordance with one aspect of the invention, a multi-sectional utility pole comprises a lower pole support section and an upper pole support section. The lower pole support section comprises a top end, a bottom end, a top region which comprises the top end, a middle region, and a bottom region which comprises the bottom end. The middle region of the lower pole support section is not tapered, but the top region is tapered so that its circumference is decreased toward the top end. The upper pole support section also comprises a top end, a bottom end, a top region which comprises the top end, a middle region, and a bottom region which comprises the bottom end. The middle region of the upper pole support section is not tapered, but the bottom region is tapered so that its circumference is increased toward the bottom end. The increased circumference of the bottom region of the upper pole support section allows it to receive at least a portion of the top region of the lower pole support section. This arrangement allows the upper pole support section to be axially mounted on the lower pole support section.
Briefly, in accordance with another aspect of the invention, a method for making the multi-sectional utility pole above comprises the steps of forming the bottom region of the upper pole support section by swaging, and forming the top region of the lower pole support section by swaging. The bottom region of the upper pole support section is formed by swaging a bottom portion of the middle region of the upper pole support section. The bottom portion of the middle region is tapered out by the swaging process and becomes the bottom region. The top region of the lower pole support section is formed by swaging a top portion of the middle region of the lower pole support section. The top portion of the middle region is tapered in by the swaging process and becomes the top region.
Briefly, in accordance with another aspect of the invention, another method for making the multi-sectional utility pole above comprises the steps of attaching the bottom region of the upper pole support section to the middle region of the same pole section, and attaching the top region of the lower pole support section to the middle region of the same pole section. The two regions of the upper pole support section are attached by welding the tapered bottom region to the middle region. This bottom region is initially separate from the middle region. The two regions of the lower pole support section are attached by welding the tapered top region to the middle region. This bottom region is initially separate from the middle region.